This invention relates to a device for controlling movement of a valve and particularly relates to an adjustable control apparatus for a hydraulic shifter. More specifically this invention relates to an adjustable slow shift control unit with built in override relief valve to control spool shifting time of a manually operated directional control valve.
Hydraulic and pneumatic systems are heretofore known and generally includes valves with spools. There have been many control units which have been designed in order to control the introduction and rate of fluid flow within such hydraulic and pneumatic systems. It is generally desirable to minimize or eliminate hydraulic shock in a hydraulic system which can be created upon rapid shifting of the spool or valve when for example one attempts to stop the fluid flow instantly; such as for example in an emergency situation.
There have been many attempts to design slow shift control units to reduce or eliminate the hydraulic shock in a hydraulic system due to rapid shifting of the spool. Such slow shifting action extends the lifetime of the hydraulic components and tends to prevent mechanisms from breaking down.
For example one such system is shown in U.S. Pat. No. Re36,342.
However many of the slow shift control systems available in the market are of the fixed type of control which does not allow fine tuning of the valve in the hydraulic system. Moreover such prior art devices have not generally been used to control manually operated directional controlled valves.
It is an object of this invention to provide an improved slow shift control unit.
It is another object of this invention to provide a control unit which is adjustable.
It is another aspect of this invention to provide a device for controlling movement of a valve comprising first and second chambers having a fluid; passage means communicating with said first and second chambers for displacement of said fluid between said chambers through said passageway upon movement of said valve.
It is a further aspect of this invention to provide an adjustable control apparatus for a hydraulic shifter comprising first and second chambers containing a fluid; a valve means moving between a first and second position; an adjustable means for controlling the rate of communication of said fluid between said first and second chambers as said valve means moves between said first and second position.
It is a further aspect of this invention to provide a method of using an adjustable control apparatus for a hydraulic shifter having first and second chambers containing a fluid comprising moving a valve means between a first and second position; adjusting and adjustable means for controlling the rate of communication of said liquid between said first and second chambers as said valve means moves between said first and second position.
It is yet another aspect of this invention to provide a method of using an adjustable control apparatus for a hydraulic shifter having first and second chambers containing a liquid comprising moving a valve means having a lever, a spool and at least one passage between a first and second position; adjustable means for controlling the rate of communication of said liquid between said first and second chambers as said valve means moves between said first and second position by engaging said lever and said spool.